Beta-blockers are a class of medications available as a prescription only. They work by blocking two chemicals from binding to beta receptors on nerves: norepinephrine and epinephrine. Beta-blockers work on beta-1 and beta-2 receptors, located in different areas of the body. Beta-1 receptors are located on the heart, eye and kidneys, while beta-2 receptors are located on the lungs, liver and muscle. All the beta-blockers block the receptor of the heart, leading to a reduction in the heart rate. They also cause relaxation of blood vessels to lower the blood pressure. Beta-blockers include atenolol (Tenormin), betaxolol (Kerlone), bisoprolol (Zebeta), metoprolol (Lopressor or Toprol XL), nadolol (Corgard), propanolol (Inderal), timolol (Blocadren), acebutolol (Sectral), carteolol (Cartol), penbutolol (Levatol), pindolol (Visken), carvedilol (Coreg) and lavetolol (Normodyne).
High Blood Pressure
Beta-blockers are used for the treatment of high blood pressure. They are often preferred when there are other indication factors, such as a heart attack or high coronary disease risk. The beta-blockers may also be added on to other medications to lower the blood pressure when there are two indicating factors; an example of this is an individual who has heart failure and diabetes.
Congestive Heart Failure
Beta-blockers may also be used for the treatment of congestive heart failure. According to "Pharmacotherapy: A Pathophysiologic Approach," beta-blockers, particularly carvedilol and metoprolol succinate, reduce deaths in patients with heart failure. It also explains that beta-blockers are useful in individuals who have had a heart attack. There is a reduced risk for heart complications when beta-blockers are administered.
Common Side Effects
The beta-blockers may cause several common side effects. Dizziness is seen in individuals on a beta-blocker. Individuals are advised to use caution when driving or performing any activity that requires alertness. Orthostatic hypotension may occur with beta-blockers, specifically in the elderly. Orthostatic hypotension is a sudden drop in the blood pressure that occurs when moving to a standing position too quickly. The elderly are not able to control changes in position and regulation of blood pressure as easily and may experience dizziness and fainting. They should rise slowly from a sitting or lying position. Diarrhea is another common side effect produced by beta-blockers. Headache may also occur when taking a beta-blocker. If any of these side effects become persistent or worsen, contact your health care provider.
Use in Diabetics
Diabetics take medications aimed at lowering the blood sugar levels. The medications will, therefore, have the ability to lower the blood sugar to a level that is too low. Individuals with a low blood sugar, called hypoglycemia, experience dizziness, nervousness, sweating and hunger. When these symptoms are present, diabetics should suck on hard candy to raise the sugar level back to normal. Beta-blockers mask the symptoms of hypoglycemia except for sweating. This may be dangerous because hypoglycemia can lead to fainting, coma and eventual death when left untreated.
Rebound Hypertension
Beta-blockers cannot be stopped without lowering the dose appropriately. The dose should be gradually decreased over time to avoid an effect called rebound hypertension. Rebound hypertension is a sharp rise in the blood pressure up to the value it was before drug therapy or even higher. This rise in the blood pressure may become dangerously high and require emergency medical help.
References
- "Drug Information Handbook 15th Edition"; Lacy, Charles F., Armstrong, Lora L., et al; 2007
- "Pharmacotherapy: A Pathophysiologic Approach"; Dipiro, Joseph T., Talbert,Robert L., et al; 2008
